Download Biomass Characteristics

Biomass Characteristics
John Langille
October 2, 2009
“Quiz”
 Biomass does not produce CO2.
 Biomass does produce CO2.
 Biomass does not make net addition to CO2.
Outline
 Definition of Biomass
 Biomass Classification
 Classification of Biomass Fuels
 Properties of Biomass
 Physical
 Thermodynamic
 Other
What is Biomass?
 Any organic material derived from plants
(botanical) or animals (biological)
 A non-fossilized fuel source that is
biodegradable
 Excludes materials normally used as foods
A Renewable Energy Source
 When biomass dies it is naturally broken
down and releases H2O, CO2, and energy
 The same change happens when used for
chemical or energy purposes
 Net pollution contribution is zero!
How is Biomass Formed?
 Botanical (plant) biomass converts CO2 and
H2O to carbohydrate and oxygen with energy
from the sun through photosynthesis
 Biological (animal) species grow by
consuming botanical species or other
biological species
Biomass Classification
A. Virgin Biomass
1. Terrestrial

Forest

Grasses

Energy crops

Cultivated crops
2. Aquatic

Algae

Water plants
Biomass Classification
B. Waste Biomass
1. Municipal waste

Municipal solid waste

Bio-solids, sewage

Landfill gas
2. Agricultural solid waste

Livestock and manures

Agricultural crop residues
3. Forestry residues

Bark, leaves, floor residues
4. Industrial wastes

Demolition wood, sawdust

Waste oil, fat
Classification of Biomass Fuels
1. Atomic ratios


H:C:O content
van Krevelen diagram (H/C versus O/C)
Classification of Biomass Fuels
1. Atomic ratios
2. Ratio of biomass components

Cellulose, hemicellulose, and lignin
Classification of Biomass Fuels
1. Atomic ratios
2. Ratio of biomass components
3. Ternary diagram

Shows biomass conversion processes in
terms of H:C:O ratio
Physical Properties of Biomass
 True density
total mass of biomass
ρtrue = solid volume in biomass
Physical Properties of Biomass
 True density
 Apparent density
ρapparent =
total mass of biomass
volume of solids and internal pores
Physical Properties of Biomass
 True density
 Apparent density
 Bulk density
ρbulk =
total mass of biomass particles or stack
bulk volume occupied by particles or stack
Physical Properties of Biomass
 True density
 Apparent density
 Bulk density
 Biomass density
 Biomass available per unit area land

Kg/hectare of a harvested crop

Oven dry tons/hectare of trees
Thermodynamic Properties of Biomass
 Thermal conductivity
 The ability of the biomass to conduct heat
 Specific heat
 The amount of heat required to raise a unit
mass of biomass by one unit of a specified
temperature
 Heat of formation
 Energy to form the biomass from its constituent
elements
Thermodynamic Properties of Biomass
 Heat of combustion
 Heat released/absorbed in a chemical reaction
without a change in temperature
 Ignition temperature
 The temperature of the biomass at which the
combustion reaction becomes self sustaining
 Heating value
 HHV – heat released by combustion of a fuel at
25°C and returned to 25°C
 LHV – heat released by combustion of a fuel at
25°C and returned to 150°C
 LHV = HHV – latent heat of vaporization
Other Properties of Biomass
 Bases of expressing biomass composition
 “As received” basis
 Ultimate analysis


Determines the composition of the biomass
fuel in terms of basic elements
C + H + O + N + S + A + M = 100%
Other Properties of Biomass
 Bases of expressing biomass composition
 “As received” basis
 Proximate analysis


Determines the composition of the biomass
fuel in terms of gross components
VM + FC + A + M = 100%
Other Properties of Biomass
 Bases of expressing biomass composition
 “As received” basis
 “Air dry” basis
 The biomass is dried in air, removing surface moisture
Other Properties of Biomass
 Bases of expressing biomass composition
 “As received” basis
 “Air dry” basis
 “Dry” basis
 The biomass completely dried, removing both surface
and inherent moisture
Other Properties of Biomass
 Bases of expressing biomass composition
 “As received” basis
 “Air dry” basis
 “Dry” basis
 “Dry and ash free” basis
 Components are reported with ash and water removed
Conclusions
 Biomass is a renewable and sustainable
alternative to fossil fuels
 There is no net pollution to the environment
 Classification of Biomass
 Properties of Biomass
 Physical
 Thermodynamic
 Other